1. Field of the Invention
The present invention is directed towards the field of tuning algorithms, and more particularly towards tuning algorithms using successive approximation.
2. Art Background
Typically, receivers employ filters to condition both input signals and internally generated reference signals. For example, bandpass, notch, and low pass are types of filters employed in receivers. The frequency response of a filter refers to the characteristics of the filter that condition the signal input to the filter. For example, a bandpass filter may attenuate an input signal across a pre-determined band of frequencies above and below a center frequency of the filter. Filters are designed to exhibit frequency responses based on one or more circuit parameters.
Some receivers are designed to process input signals with a range of input carrier frequencies (e.g., wide band receivers). For example, television receivers must be capable of processing input television signals with carrier frequencies ranging from 55 MHz to 880 MHz. One circuit parameter used to define the frequency response of a filter is the carrier frequency of an input signal. Thus, such wide band receivers require filters to generate multiple frequency responses to accommodate multiple input carrier frequencies. To accomplish this, some receivers employ tunable filters to process a wide band of input frequencies.
Tuning systems and algorithms are employed in the various types of tunable filters to tune the filter to a desired frequency, e.g., a channel frequency of a television channel. Tuning systems and algorithms are typically dependent on the type of filter to be tuned and thus are not easily made compatible with other types of filters. Also, conventional tuning systems and algorithms are hardware intensive. Therefore, there is a need for a tuning system and algorithm that is simple, accurate, and easily made compatible with various types of tunable filters.